The present invention relates to support structures, and, more particularly, to a self-stabilizing trestle that can be used as a sawhorse, scaffolding base, or similar support. Such support structures are generally comprised of a crossbeam that defines a substantially horizontal support surface that is supported by a pair of leg assemblies or legs. In their simplest form, the legs of these support structures are rigidly secured to the crossbeam, thereby preventing any movement of the legs relative to the crossbeam. Rigid attachment of the legs to the crossbeam, however, can be antithetical to the objective of providing a stable support base, as the support structure can not always be positioned on even terrain. Specifically, if one of the legs of such a support structure is not firmly resting on the underlying terrain, the structure may wobble and/or sway. Furthermore, if the support structure is used to support a board or other item for sawing, the reciprocating motion induced by sawing may cause the support structure to walk, creating unsafe conditions and discomfort for the user, and making it difficult to use a saw or similar tool with a high degree of precision. Finally, if one of the legs is not firmly resting upon the underlying terrain, structural integrity may be compromised.
Although rigid attachment of the legs to the crossbeam is still common, there are sawhorses and similar support structures in the prior art that provide for some pivotable attachment of the legs to the crossbeam. For example:
U.S. Pat. No. 1,680,065 (issued to Proctor) discloses a foldable support in which legs are attached to an upper body through pivot pins. However, the legs pivot independently for the sole purpose of making the platform smaller during transportation and storage.
U.S. Pat. No. 3,078,957 (issued to Larson) discloses a collapsible sawhorse bracket assembly, which includes a pivot pin that creates a clamping leverage. However, once the legs are in the operative position, the legs no longer pivot relative to the crosspiece. Therefore, this sawhorse is not self-stabilizing.
U.S. Pat. No. 5,207,290 (issued to Torok) discloses a hinge for a folding sawhorse. However, the leg assemblies pivot independently for the sole purpose of making the sawhorse smaller during transportation and storage.
U.S. Pat. No. 5,626,205 (issued to Martin) also discloses pivoting legs attached to a portable work platform. Again, however, the legs pivot independently for the sole purpose of making the platform smaller during transportation and storage.
Although the above prior art references teach various means by which to pivot or fold the legs of a sawhorse or similar support structure for transportation, storage, or similar purposes, none of these references addresses the objective of providing a stable support base on uneven terrain. Nevertheless, in the prior art, there have also been some attempts to provide a means by which to level or otherwise adapt a sawhorse or similar support structure for placement on uneven terrain. For example:
U.S. Pat. No. 5,007,502 (issued to Shapiro) discloses a self-leveling sawhorse. The legs are connected to the traverse cross bar through rods that are in a lateral, perpendicular orientation to the cross bar. The self-leveling properties of this sawhorse are derived from sliding the leg assemblies in a lateral direction. However, a disadvantage of such a design is that the cross bar does not have good rotational stability.
U.S. Pat. No. 3,204,906 (issued to Henderson) discloses a stabilized four-legged table, which has two legs rigidly attached to the table top, and an assembly with two legs that are pivotally attached to the table top. Although this table has four feet, the stabilizing properties are geometrically no different than a table top with three feet.
U.S. Pat. No. 5,660,303 (issued to Winters) discloses a self-stabilizing base for a table that includes a means for rotatably attaching one leg assembly to a central support while a second leg assembly is rigidly attached to the central support. Although this table base has four feet, the stabilizing properties are geometrically no different than a base with three feet. Winters recognizes this deficiency by stating that the central support will wobble rather than the legs. To prevent wobbling of the central support, Winters introduces friction in the pivoting attachment. Although sufficient friction will eliminate wobbling of the central support, in effect it also eliminates self-stabilization of the feet.
U.S. Pat. No. 5,865,269 (issued to Eskesen) discloses a work support that allows for both height adjustment and leveling. Specifically, leveling and stabilization is accomplished by manually adjusting the length of at least one leg. Although this concept provides for stabilizing the workbench on uneven terrain, the stabilization is not automatic and may need to be redone each time the workbench is moved to another location.
U.S. Pat. No. 6,283,250 (issued to Asher) discloses a portable and adjustable workbench in which the legs can be adjusted in length. The work support is stabilized by manually adjusting the length of at least one leg. Although this concept provides for stabilizing the workbench on uneven terrain, the stabilization is not automatic and may need to be redone when the workbench is moved to another location.
Finally, Applicant is aware of various commercially available sawhorses that can be considered to be “self-stabilizing” because of the torsional flexibility of the crossbeam. Such a design, however, results in a sawhorse with limited load bearing capacity as torsional flexibility is essentially a deformation caused by a lack of strength.
Although the above prior art references discuss the problem of placement of a sawhorse or similar support structure on uneven terrain, these references either do not provide for “automatic” leveling (i.e., require some manual adjustment), or have limited strength because adjustment or leveling is based on the distortion of deformation of structural components of the sawhorse or support structure.
It is therefore a paramount object of the present invention to provide a self-stabilizing support structure, a trestle, that automatically adjusts for placement on uneven terrain, thereby maintaining the stability of the trestle without sacrificing the strength or structural integrity of the trestle.
This and other objects and advantages of the present invention will become apparent upon a reading of the following description along with the appended drawings.